package JUC.rw;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * ReadWriteLock
 */
public class ReadWriteLockDemo {
    public static void main(String[] args) {
        //线程操作资源类
        MyCache myCache = new MyCache();
        //写入操作
        for (int i = 1; i <= 5; i++) {
            //进行转换
            final int temp=i;
            new Thread(() -> {
            myCache.put(temp+"",temp+"");
            }, String.valueOf(i)).start();
        }

        //读取操作
        for (int i = 1; i <= 5; i++) {
            //进行转换
            final int temp=i;
            new Thread(() -> {
                myCache.get(temp+"");
            }, String.valueOf(i)).start();
        }
    }
}

/**
 * 自定义缓存
 */
class MyCache{
    private volatile Map<String,Object> map =new HashMap<>();

    //存,写
    public void put(String key,Object value){
        System.out.println(Thread.currentThread().getName()+"写入"+key);
        map.put(key, value);
        System.out.println(Thread.currentThread().getName()+"写入OK");
    }

    //取,读
    public void get(String key){
        System.out.println(Thread.currentThread().getName()+"读取"+key);
        Object o = map.get(key);
        System.out.println(Thread.currentThread().getName()+"读取OK");
    }
}

/**
 * 加锁的自定义缓存
 */
class MyCacheLock {
    private volatile Map<String, Object> map = new HashMap<>();
    //更加细粒度的控制
    private ReadWriteLock lock=new ReentrantReadWriteLock();

    //存,写入时，同时只有一个线程写
    public void put(String key, Object value) {
        lock.writeLock().lock();

        try {
            System.out.println(Thread.currentThread().getName() + "写入" + key);
            map.put(key, value);
            System.out.println(Thread.currentThread().getName() + "写入OK");
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
                lock.writeLock().unlock();
        }

    }

    //取,读所有线程都可以读
    public void get(String key) {
        lock.readLock().lock();

        try {
            System.out.println(Thread.currentThread().getName() + "读取" + key);
            Object o = map.get(key);
            System.out.println(Thread.currentThread().getName() + "读取OK");
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
                lock.readLock().unlock();
        }

    }
}